1. Field of the Invention
The present invention relates to a method of transmitting data using a relay, and more particularly, to a signaling method of determining an optimal transmission mode using a relay, and a frame structure for determining an optimal transmission mode using a relay.
2. Description of Related Art
With the development of wireless communication networks, various communication services such as simple voice communication, data transmission for video conferencing, and the like, based on wireless technologies have been gradually introduced.
The communication quality of a digital communication system is controlled in accordance with a ratio of the strength of a transmitted data signal to the strength of an interference signal and noise. However, the strength of the transmitted data signal deteriorates over time due to wireless channel characteristics. Thus, in a conventional mobile communication technology, a wireless terminal using a specific communication service cannot ensure its communication quality due to a fading phenomenon where a wireless channel varies over time.
In this regard, a scheme in which a predetermined Signal to Interference and Noise Ratio (SNIR) value is set, and the strength of a transmitted data signal is controlled based on the set value has been suggested. However, in the case where the wireless channel varies rapidly, the scheme cannot ensure communication quality.
In order to overcome the above-mentioned fading phenomenon, various diversity schemes have been used. In particular, a space diversity scheme for transceiving data using a plurality of antennas placed apart spatially from one another has been widely used as a simple scheme that is effective for overcoming the fading phenomenon.
The space diversity scheme may be used for the case in which a relatively larger space where antennas are installed is provided, such as a base station or an access point; however, it cannot be used in the case where a relatively smaller space in which antennas are installed is provided, such as a terminal.
Therefore, for overcoming the above-mentioned shortcoming, a data transceiving method using a relay has been proposed. This method is performed such that a relay receives data from a base station and forwards the received data to a terminal, and the terminal receives the data via a path having a relatively superior channel state, which corresponds to either a path from a base station to a terminal or a path from a relay to a terminal.
However, in the data transceiving method, a specific signaling process and data frame structure for determining an optimal path from among paths connecting the base station, the relay, and the terminal with one another have not been suggested, and thus a problem in substantially transmitting data arises.